以下程序应该接收4位颜色代码电阻的用户输入，然后继续在JFrame中打印它（目前为BufferedReader和JFrame设置了它）但是，我知道我不能简单地打印一些东西将外部方法转换为内部方法。例如，我试图在输入完成后在动作监听器中打印array3，但是我得到了这个错误。
我试图在主要方法中将某些变量设置为final，通过互联网搜索了各种页面，但仍无法找到解决我特定问题的方法。我之前在这里确实问过这个问题，然而，由于尝试用自己的方法重新编写我的代码JFrame导致接近混乱，导致更多的混乱，因此我不得不回到原始代码。我想知道如何获取用户输入并将其传递给下面的那些方法在JFrame上，因为我现在正在尝试的东西肯定不起作用。
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.Arrays;
import javax.swing.JFrame;
public class test extends JFrame
{
public static void main (String [] args) throws IOException
{
BufferedReader myInput = new BufferedReader (new InputStreamReader (System.in));
//calling variables
String input;
int numInput;
JLabel l = new JLabel("Hello and welcome to the Program");
l.setAlignmentX(0);
l.setAlignmentY(0);
//calling arrays
int [] array = new int [5];
int [] array2 = new int [3];
String [] array3 = new String [3];
String[] colours = {"black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "gray", "white"};
String[] tollerance = {"red", "gold", "silver", "no band"};
JFrame f = new JFrame("Hello JFrame");
f.setSize(500,500);
//f.getContentPane().setBackground(Color.CYAN);
f.add(l);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
f.setLocationRelativeTo(null);
//JTextField t = new JTextField(16);
/*SodaMachine machine = new SodaMachine(); //class name
JButton cokeButton = new JButton();
cokeButton.addActionListener(new ActionListener() {
public void actionPerformed() {
machine.dispenseCoke();
}
}); */
JPanel p = new JPanel ();
JButton b = new JButton("Press me") ;
b.setAlignmentX(0);
b.setAlignmentY(0);
test x = new test();
b.addActionListener(new ActionListener(){
public void actionPerformed (ActionEvent e) {
JOptionPane.showMessageDialog(null,"In the following program you (The user!) will input a number of a resistor value \nThe program will pass the information into methods and then proceed to print out \nThe coorelating colors (Press the button to be asked for input)");
int number = Integer.parseInt(JOptionPane.showInputDialog("Please enter the resistor value"));
JOptionPane.showMessageDialog(null, "The Colors are : " + array3[i]);
}
});
p.add(b);
p.add(l);
//p.add(t);
f.add(p);
System.out.println("Hello and welcome to the Program (Press any key to con't)");
input = myInput.readLine ();
System.out.println("In the following program you (The user!) will input a number of a resistor value");
System.out.println("The program will pass the information into methods and then proceed to print out");
System.out.println("The coorelating colors (Press any key to be asked for input)");
input = myInput.readLine();
System.out.println("Enter a resistor value (Note that resistors can only acount to 4 decimal places");
input = myInput.readLine ();
numInput = Integer.parseInt (input);
//colours for values
array2 = values(array, input, colours);
for(int i = 0 ; i < 3; i++){
array3[i] = digitColours(array2[i], colours);
System.out.println(array3[i]);// prints colours for values
}
//prints 4th colour for multiplier
System.out.println(decimalPlaces(input, colours));
//tollerance band
System.out.println(tollerance(input, tollerance));
}
public static int[] values (int [] digit, String num, String[] colours)
{
String holder;
double numHolder;
int lengthOfInput;
int holder2;
//Rounding of the input
lengthOfInput = num.length() - 3;
numHolder = Double.parseDouble(num);
numHolder = numHolder/(Math.pow(10,lengthOfInput));
numHolder = (int)(Math.round(numHolder)+0.5);
// first three digits
for(int i = 0; i < 3; i++){
holder = num.substring(i,i+1);
digit[i] = Integer.parseInt(holder);
}
return new int[] {digit[0], digit[1], digit[2]} ;// return
}
public static String digitColours(int decimalPlace, String[] colours){
//calling additional variables
String answer;
answer = colours[decimalPlace];
return answer;
}
//method to find the multiplier
public static String decimalPlaces(String input, String[] colours){
//calling additional variables
int length = input.length();
String answer;
length = length - 3;
answer = colours[length];
return answer;
}
public static String tollerance(String num, String[] tollerance){
String holder;
int holder2;
double perError;
//tollerance
holder = num.substring(3,4);
perError = Double.parseDouble(holder);
holder2 = Integer.parseInt(num);
// checks to see if above 5
if(perError < 5){
perError = perError/holder2 * 100;
}
else if(perError > 5){
perError = 10 - perError;
perError = perError/holder2 * 100;
}
//changing for colour
if(perError <= 2){
perError = 0;
}else if(perError <= 5){
perError = 1;
}else if(perError <= 10){
perError = 2;
}else if(perError <= 20){
perError = 3;
}
return tollerance[(int)perError];
}
}
答案 0 :(得分：6)
您的短期问题是您正在尝试在内部类中使用本地方法的非final变量。这可以通过使用final变量或类字段来解决（这里，因为它在静态方法中使用，它必须是静态的）。
但话说回来，你的整体问题 再次 就是你已经把所有东西都塞进了静态主方法（或任何类型的静态方法）物）。您绝对需要创建可用于创建对象的类。我相信我们之前讨论过这个问题。
修改
我已经改变了主意 - 你的“模型”，你的代码决定了显示什么颜色的字符串可能只包含静态方法。它可能有一个看起来像这样的方法：
public class ResistorColorsUtility {
// create a String array, ALL_COLORS, as a constant that the methods
// of this class can use.
private static final String[] ALL_COLORS = { "black", "brown", "red",
"orange", "yellow", "green", "blue", "violet", "gray", "white" };
public static String[] getColorsForValue(int value) {
// code in here will create an array of Strings for the value given and
// return it
// here use value int to find all the appropriate colors
// create String array called result to hold the color Strings
String[] result = ......; // you've got to create this code!
return result; // return the result
}
// it will likely have other public methods that the GUI could use
// and other private methods that it will only use internally
// and will not be used by other classes
}
GUI具有用于输入和显示结果的字段，以及用于找出用户何时想要查看结果的按钮。 main方法只是让程序运行，这里创建一个JFrame来放置主GUI代码的JPanel，然后显示该JFrame。
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
// A very simple GUI to illustrate a point
public class ResistorGui extends JPanel {
private JButton findColorButton = new JButton("Find Colors");
private JTextField valueInputField = new JTextField(2);
private JTextField resultField = new JTextField(15);
public ResistorGui() {
// user shouldn't be able to edit result field
resultField.setEditable(false);
resultField.setFocusable(false);
findColorButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// all program logic is in here
// get value String from valueInputField
// translate to int
// call utility method from ResistorColorsUtil class!
// display result in resultField
}
});
add(new JLabel("Value:"));
add(valueInputField);
add(findColorButton);
add(new JLabel("Result:"));
add(resultField);
}
// all main does is to display the GUI, that's it
public static void main(String[] args) {
ResistorGui mainPanel = new ResistorGui();
JFrame frame = new JFrame("ResistorGui");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}